Disease is often overlooked as a natural disturbance agent in plant communities. This study examines what effects, if any, a disease-mediated disturbance has on the plant community as a whole in old-growth and mature forests of western Oregon. Phellinus weirii (Murrill) Gilbertson (Family: Hymenochaetaceae) is a native root-rotting pathogen that...
The main objective of this thesis was to determine the influence of tree vigor on susceptibility to Armillaria root disease. First, the effect of thinning, fertilizing and pruning on tree vigor of four young Douglas-fir (Pseudo tsuga menziesii var. menziesi,) plantations was explored. Tree vigor was calculated by measuring wood...
Decomposing logs in Douglas-fir - western hemlock forests in the Pacific Northwest are systems in which many organisms interact. Fungi in these systems include both mycorrhizal fungi associated with hemlock seedlings and many species of saprotrophic wood decomposer fungi. It is very likely that these two groups of fungi interact...
The septoria diseases of winter wheat are a limiting factor to wheat production in the Willamette Valley. This publication will describe the symptoms and development of the septoria diseases, including the influence of environmental conditions, the reactions of different cultivars to Septoria, the impact of Septoria on yield, and control...